Magnetic switching device



Dec.. 2l, 1954 R, F. KRUPP ETAL MAGNETIC swITcHING DEVICE INVENTORS` Filed June 9, 1952 R0 ERT E K/'PUPP PAZL F. EAV/T7' /dwnwdM/dwnaud United States Patent Office y 2,697,513 Patented Dec. 21, 1954 2,697,513 MAGNETIC SWITCHING DEVICE Robert F. Krupp and Paul F. Leavitt, San Lorenzo, Calif., assignors to Gerber Products Company, Fremont, Mich., a corporation of Michigan Application .lune 9, 1952, Serial No. 292,568 7 Claims. (Cl. 209-72) This .invention relates to a switching device wherein a magnetic attractive object moving along a conveyors is .switched from one path to another path, the switching instrumentality comprising an electromagnet. By varying the magnetic force imparted to the object or by varying the duration of the application of the magnetic force, the object may be switched to any of a plurality of different paths or tracks.

The actuation of the switch controlling the passage of current through the coils of the electromagnet may be accomplished in many different ways depending upon the purpose of the switching operation. For example, let it be assumed that a plurality of tin cans move along a conveyor in a straight line and that some of the cans are marked with a peculiar indicium, and let it further be assumed that it is desired to segregate those cans bearing the indicium from the remaining cans. The cans may be passed through the field of view of a photo-electric cell sensitive only to those cans bearing the indicium so that the cell is energized only by the cans to be segregated. As the cans pass the photo-electric cell they also pass an electromagnet which is energized by the photo-electric cell closing a relay and the magnet draws the cans out of line and switches them into a second line.

Another adaptation of the invention is in connection with detecting overweight and underweight cans. Thus the cans are passed over a scale which actuates one electric switch for the cans which are overweight and a diiferent electric switch for the cans which are underweight, said switches being in the circuit of the electromagnet, there being a greater resistance in the circuit of one electric switch than the other. Thus, cans which are of standard weight actuate neither switch and continue in a straight line, whereas underweight cans are pulled out by the magnet and shifted into a second discharge line and cans which are overweight are switched into a different discharge line.

The foregoing applications of the invention are merely illustrative. Actually, the switch closing the circuit of the electromagnet may be manually controlled. It is understood that some sort of electric switch is installed in the circuit of the coils of the electromagnet, the type switch and the means for closing same being subject to wide modification.

The objects which may be handled by the instant device include any objects consisting in whole or in part of a metal which is subiect to magnetic attraction. One of the most useful applications of the invention is in separating steev containers or glass containers with steel caps.

Heretofore segregation by switching objects from one path to another has been accomplished in various ways, but the actual switching device has comprised moving parts, such as swinging gates, moving pins, levers and the like, which were actuated by cams, solenoids and pneumatic or hydraulic motors. All of the foregoing devices have moving parts which are subject to wear and require maintenance. Further, the said devices have certain inertia and time lag inherent in their operation which limit the speed at which they may be operated. The present invention eliminates the foregoing objections to prior switching devices by using a standard electromagnet and has no moving parts other than the moving elements of the electric switch in the electric circuit of the magnet, 'said moving elements being very light in weight and very durable. Thus, in essence, the instant invention ycomprises Aa .stationary electric magnet which attracts close electric switches 31 and a moving line of objects by reason of the closing of an electric switch in the circuit of the electromagnet. The magnet is energized upon closing of the switch for an instant sufficient to impart an acceleration to the selected object in a direction at an obtuse angle with respect to the path of movement of the object. Desirably the magnet is de-energized as the object enters the center of the magnetic field and thus the inertia of the object which has been accelerated propells the object beyond the magnet and into a different line from that in which it has been traveling. By variation of magnetic force of the magnet or the duration thereof the lateral displacement of the object may be controlled. Thus, by applying dierent magnetic forces the objects may be switched into corresponding different discharge lines.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

Fig. l is a side elevation of a invention is installed.

Fig. 2 is a top plan thereof with the hood of the detecting mechanism removed.

Fig. 3 is a section taken substantially along the line 3 3 of Fig. 2.

Fig. 4 is a schematic wiring diagram.

As illustrated in the accompanying drawings, there is provided a link or belt conveyor 10 which moves continuously at a relatively constant speed around two pulleys 11 and 12 at opposite ends of a frame 13, one of said pulleys 11 being driven by an electric motor 14. The direction of movement of the top stretch of conveyor 10 as viewed in Fig. l is to the left. It will be understood that instead of a moving conveyor a downwardly inclined chute may be employed to convey the objects to be segregated, but it has been found that a positively moving conveyor performs more effectively, particularly at higher speeds.

Along one longitudinal edge of the conveyor is disposed a first and a second parallel guide rail 16 and 17 which are separated a distance equal to the diameter of the cans 18 or other objects being segregated and confine the path of the cans to a straight line. Said rails 16 and 17 are placed immediately above the surface of the conveyor 10. The cans 18 so conveyed are passed through the field of a detecting apparatus 19 which may be photo-electric cells 21 and 22 receiving refiected light from light sources 23 and 24, a scale, or any other device which will detect the cans to be separated from other cans. One cell 21 may be affected, for example, only by light of one color with which the tops of certain cans 18 may be painted, while cell 22 may be affected only by a different color with which other cans are painted. Cells 21 and 22 actuate relays 26 and 27 respectively, to 32 respectively, in a direct current circuit. It will be assumed that certain objects will not actuate the detecting switches 31 or 32 and will continue in a straight path, whereas other objects will be detected and close one or the other of said electric switches 31 and 32. It will be understood that a single switch may be employed rather than the two switches 31 and 32 herein illustrated, and it will further be understood that more than two switches may be employed.

As the can passes the detecting device 19 the cans also pass through the magnetic field of an electromagnet 33 having its core 34 disposed at an angle to the path of the cans. The optimum angle for proper switching of size 202 X 214 cans traveling at the rate of Q cans per minute is 41 as indicated in Fig 2. The optimum angle of the core of magnet 33 with respect to the path of the cans for cans of different mass and cans traveling at different speeds will vary within a few degrees. The inner guide rail 17 is discontinuous immediately beyond the electromagnet 33 to permit lateral displacement .of the cans in the direction of the magnet. Laterally displaced from the second rail 17 are third and fourth rails 36 and 37 likewise suspended immediately above the conveyor and which define a second and a third discharge line for the cans.

selected objects from conveyor on which the The electric circuit is illustrated in Fig. 4 and as shown comprises a source of direct current 38, a first switch 31 connected in series with the coil of electromagnet 33, and a time delay switch 39, and a second switch connected in series with a fixed resistance 41, the coil of the electromagnet 33 and the time delay switch 39.

The operation of the device is as follows:

Cans 18 are deposited serially on the upper stretch of a conveyor 10 between first and second guide rails 16 and 17 and are conveyed past the detecting device 19 which may close either the first switch 31, second switch 32, or neither switch, depending upon the condition of each specific can. Assuming that neither electric switch 31 or 32 has been closed, the cans continue along a straight line and are received in the first discharge line 42 between the first and second guide rails 16 and 1'/ beyond the electromagnet 33. Assuming that the first switch 31 has been energized, said switch having resistance 41 in series, the amperage through the electromagnet 33 is limited and upon energizing of the electromagnet for a fixed period of time on acceleration is imparted to the can to cause the can to veer out of line a fixed lateral displacement such that it is received between the second and third guide rails 17 and 36 in the second discharge line 43 and carried along by the conveyor 11). Assuming that the second switch 32, which has no extra resistance in series, is closed, a greater amperage passes through the coils of the electromagnet 33 for a fixed interval of time and hence a greater acceleration is imparted to the can which causes it to continue past the third guide rail 36 and 'oe received between the third and fourth guide rails 36 and 37 and thus deposited in the third discharge line 44 The period of time during which magnet 33 is energized is limited by time delay 39 to a brief interval which is only sufiicient to draw the can toward the center of the magnetic field and thus impart an acceleration to the can. Desirably the magnet 33 is de-energized by timedelay switch 39 before the attracted can or other obn ject has entered the center of the magnetic field. The inertia of the can tends to cause the can to continue its lateral displacement. The greater the current through the magnet, the greater the acceleration imparted to the can and the greater its displacement from a straight It will be obvious to those skilled in the art to which this invention appertains that the three lines of cans may be separately handled and conveyed upon reaching the end of the upper stretch of the conveyor belt.

As has been indicated, although three discharge lines 42, 43 and 44, have been illustrated and described, any number greater than two may theoretically be employed. Thus, a single switch may be used in conjunction with the detecting apparatus to switch the cans line to a second line. On the other hand, by employing three or more switches, each having a different resist ance in series, four or more discharge lines may be established.

from a first 4 Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention and scope of the appended claims.

What is claimed is:

l. A magnetic switching device comprising first means for conveying magnetizable objects along a feed path, an electromagnet offset horizontally to one side ofv said feed path, an electric switch selectively operable to energize said magnet and arranged when energized to aceelerate one of said objects in a direction horizontally oblique to said feed path, and means dening a plurality of discharge paths, one of said discharge paths comprising a projection of said feed path and another of said discharge paths being horizontally laterally displaced therefrom in the direction of magnetic attraction of said magnet.

2. A switching device according to claim l in which is further provided a time-delay switch for cie-energizing said magnet before the attracted object has entered the center of the magnetic field.

3. A switching device according to claim l in which the polar axis of said magnet is disposed at an acute angle with respect to said feed path.

4. A magnetic switching device comprising a conveyor for advancing magnetizable objects along a feed path, a first guide rail adjacent one longitudinal edge of said conveyor, a second guide rail parallel to and spaced inwardly from said first rail, said first and second rails defining said feed path, an electromagnet laterally offset with respect to said second guide rail, said second guide rail being interrupted immediately beyond said magnet, and a third guide rail beyond said magnet parallel to and spaced inwardly from said second rail, and an electric switch selectively operable to energize said magnet to magnetically attract one of said magnetizable objects to accelerate one of said objects in a direction oblique to said feed path to displace said object laterally into a discharge path between said second and third rails.

5. A device according to claim 4 in which is further provided a time switch to de-energize said magnet before said object enters the center of the field of said magnet.

6. A magnetic switching device comprising a conveyor for advancing magnetizable objects along a feed path, a first guide rail adjacent one longitudinal edge of said conveyor, second, third and fourth guide rails parallel to and spaced consecutively inwardly from said first rail, said first and second rails defining said feed path, an electromagnet laterally offset with respect to said second rail, said second rail being interrupted immediately beyond said magnet, said third and fourth rails having their upper termini beyond said magnet, a first electric switch selectively operable to energize said magnet to accelerate an object being conveyed in a direction oblique to said rails to laterally displace said object a distance sufficient for said object to be received between said second and third rails, and a second electric switch selectively operable to energize said magnet to accelerate an object being conveyed in a direction oblique to said rails to laterally displace said object a distance sufficient Afor said object to be received between said third and fourth rails.

7. A device according to claim 6 which further includes a time-delay switch for de-energizing said magnet after an interval sufficient to impart an acceleration to said objct sufiicient to carry said object into said discharge pat.

References Cited in the file of this patent UNITED STATES PATENTS 

